The present invention relates generally to a system including a preemphasis driver circuit, a method for operating a system preemphasizing an input signal to drive an output terminal and a method for driving a loaded transmission line with preemphasis.
The preemphasis of a data signal is a known method of improving the signal integrity of data transmitted to a receiving terminal and in particular if the data is transmitted over long or lossy transmission lines. Normally higher frequency spectral components of a data signal are affected by stronger channel attenuation.
Therefore, increasing the data rate of the data signal, or increasing the length or the losses of a transmission line loaded at a receiving terminal, leads to an increasingly closed eye aperture when the transmitted data signal is analyzed using eye diagrams. This increasingly closed eye diagram corresponds to an increasing corruption of the data signal meaning that it becomes more and more difficult to reconstruct the correct signal value at the receiving terminal.
Basically, as a countermeasure preemphasis can be used to predistort the signal to be transmitted by increasing or emphasizing the higher order harmonics in the signal to be transmitted. In other words, preemphasis leads to a compensation of the low-pass behavior of the transmission channel (e.g., a lossy transmission line) through usage of a driver with high-pass filtering behavior.
However, known realizations of preemphasis driver circuits suffer from various structural and implementational disadvantages.
For these or other reasons, there is a need for the present invention.